a: \(\left(\dfrac{7}{8}-\dfrac{5}{2}+\dfrac{4}{7}\right)-\left(-\dfrac{3}{7}+1-\dfrac{13}{8}\right)+\dfrac{3}{5}-\left(-\dfrac{2}{7}\right)\)
\(=\dfrac{7}{8}-\dfrac{5}{2}+\dfrac{4}{7}+\dfrac{3}{7}-1+\dfrac{13}{8}+\dfrac{3}{5}+\dfrac{2}{7}\)
\(=\left(\dfrac{7}{8}+\dfrac{13}{8}-\dfrac{5}{2}\right)+\left(\dfrac{4}{7}+\dfrac{3}{7}+\dfrac{2}{7}\right)-1+\dfrac{3}{5}\)
\(=\dfrac{9}{7}-\dfrac{2}{5}=\dfrac{45}{35}-\dfrac{14}{35}=\dfrac{31}{35}\)
b: \(-\dfrac{3}{7}+\left(3-\dfrac{3}{4}\right)-\left(2,25-\dfrac{10}{7}\right)\)
\(=-\dfrac{3}{7}+3-\dfrac{3}{4}-\dfrac{9}{4}+\dfrac{10}{7}\)
\(=1-3+3=1\)
\(\left(\dfrac{7}{8}-\dfrac{5}{2}+\dfrac{4}{7}\right)-\left(-\dfrac{3}{7}+1-\dfrac{13}{8}\right)+\dfrac{3}{5}-\left(-\dfrac{2}{7}\right)\)
\(=\dfrac{7}{8}-\dfrac{5}{2}+\dfrac{4}{7}+\dfrac{3}{7}-1+\dfrac{13}{8}+\dfrac{3}{5}+\dfrac{2}{7}\)
\(=\left(\dfrac{7}{8}+\dfrac{13}{8}\right)-\dfrac{5}{2}+\left(\dfrac{4}{7}+\dfrac{3}{7}+\dfrac{2}{7}\right)+\dfrac{3}{5}-1\)
\(=\dfrac{5}{2}-\dfrac{5}{2}+\dfrac{9}{7}-\dfrac{2}{5}\)
\(=\dfrac{31}{35}\)
\(-\dfrac{3}{7}+\left(3-\dfrac{3}{4}\right)-\left(2,25-\dfrac{10}{7}\right)\)
\(=-\dfrac{3}{7}+3-\dfrac{3}{4}-\dfrac{9}{4}+\dfrac{10}{7}\)
\(=\left(-\dfrac{3}{7}+\dfrac{10}{7}\right)-\left(\dfrac{3}{4}+\dfrac{9}{4}\right)+3\)
\(=1-3+3\)
`=1`
